That internal combustion engines provide a lot of waste heat inspired my father to suggest mounting a Stirling (external combustion) engine on the exhaust manifold or catalytic converter. He made that suggestion 25 years ago. It is still a good idea.
While we are at this, let's not forget that a lot of the gas in an automobile is used simply to keep the motor running. Cylinder type engines have a minimum speed below which they will not function at all. Any time you are below that speed (except during acceleration), you are pumping 100% of that gas into just keeping the engine from stalling. The vehicle is coasting. Reducing this problem is what a transmission is for. It is also why "instant start" engines have gained favor.
Also, an automatic transmission is a terribly inefficient device. It requires a fluidic clutch. In point of fact, "automatic overdrive" is nothing more than a means of bypassing the fluidic clutch when the engine speed is high enough that the transmission isn't needed.
Thanks for the link, J. Williams. I have recently written about an energy-harvesting shoe insert, and this seems like something along those lines. Not sure it's a good application for a car, though! ;)
Thanks for that perspective, Watashi. I don't know much about this air ride technology--do you mean in big tractor-trailer-type vehicles? I know these guys are targeting heavy trucks like Hummers and such. Do they have this air ride already?
The "improved ride" might be applicable to smaller trucks and cars, but they will have an uphill battle competing against air ride suspensions in big trucks. Shocks would be a step back in technology.
Air-ride not only adds comfort, but also road stability. It can level the truck against high crosswinds which is very important along the highway in most of the country. This stability no only keeps the rig right-side up and out of the ditch, but can improve mileage as well.
Thanks for the perspective, ttemple, and you bring up a good point that I also want to clarify. I don't think researchers here are expecting to double the mileage, but to power other electronics using the energy harvested. The shock absorbers themselves that they're created also are meant to work better than other shock absorbers out there--ie, cushion the blow more, as you said. I guess it does work better if you're riding on a kidney-busting road than a flat surface, but still I think this technology could be put to good use.
These are all good points to put this in perspective, William K. I suppose the success of the technology won't be proven until there's been widespread testing. The proof, as always, will be in the execution and commercialization--this might be another great idea but just not viable. And you're right, it may end up being cost-prohibitive and not worth the power the system generates.
Indeed, Lou, no surprise about MIT coming up with this. I would say the bulk of some of the most interesting things I coer are out of MIT. They really seem to give their students a wide berth in terms of innovation and guidance. I don't know about this patent program you talk about but if it encourages these technologies to come out of the lab and into the commercial market, that is a real boon.
Wow, it's great to see all the comments on this story! I have been away from the website for a few days but I will catch up soon on all of your comments. I'm glad to see this stirred such a lively commentary and interest from our readers.
The comments about recovering energy while walking bring to mind that old saying, "No such thing as a free lunch", which in this case does indeed mean that additional effort would be required to be converted into electrical power by some means. A piezo device driven by shoe flexing would demand a bit more effort to do that flexing, and a device to collect the impact energy would provide some damping of the walking effort. That was the case of the power generating sidewalk presented a while back. The deflection as folks walked on it increased the energy needed to walk on it, so people didn't walk on it as much after a while. So free energy is not everywhere, although it can be found in a few places. Wind, waves, noise, and light. The noise powered generation was first published quite a few years back. Somebody put a big set of loudspeakers on a balcony near the ocean and was able to recover an easily measureable quantity of power.
Excellent points, ttemple. The amount of energy gathered needs to be put into perspective in order to be understood. The duration of a 1 kW shock pulse is probably just a second or so -- a very, very tiny fraction of the 24-kWh capacity of, for example, a Nissan Leaf battery. You would need to drive down a washboard road for hours to re-charge your electric car battery that way.
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